1. Field of the Invention
The invention relates to an earplug compression device which aids in insertion of a slow-recovery earplug into the human ear canal.
2. Description of the Related Art
U.S. Pat. No. RE. 29,487 (Gardner, Jr.) describes earplugs of generally cylindrical shape and of somewhat larger diameter than the human ear canal. The earplugs are composed of a foamed plasticized polymeric material having a sufficiently high concentration of plasticizer to provide the earplug with a reduced rate of recovery from compression. The earplugs can be compressed by twirling lengthwise between the fingers. The compressed earplug is inserted into the ear canal where it then recovers slowly until it conforms to and obturates the ear canal, thus suppressing or attenuating the transmission of noise.
Booklet No. 1-589-5M-HP (1988), "How To Make Sure You Get The Best Fit From Your E-A-R Plugs", available from Cabot Corp. describes a device for training people to use slow-recovery earplugs of the type described in the Gardner patent. The device includes a Roll Model.TM. transparent block having cylindrical holes of graduated size. An uncompressed earplug is rolled between the fingertips until tightly compressed to form a very thin crease-free cylinder. The adequacy of compression is then evaluated by determining into which, if any, of the holes in the Roll Model.TM. block the compressed earplug will fit. When proper compression techniques have been learned, the compressed earplug can be inserted in the ear to a depth of about 1/2 the length of the ear canal. The booklet indicates that acquiring such skills is necessary because insertion into the ear canal to lesser depths causes wearers' perception of their own voices and body noises to be distorted, wearers with larger ear canals may push an earplug in so forcefully and quickly that it becomes difficult to grasp and remove as well as uncomfortable. To guard against this, the earplug can be rolled into the shape of a golf tee.
U.S. Pat. No. 4,774,938 (Leight) discloses a slow recovery earplug which has open cells for expelling gas to the outside during compression, but which resists the entry of water through the outside and the soiling of the outside by dirt. The earplug includes a body formed of pressure-molded slow recovery resilient foam material forming multiple gas-filled shells. The plug body has a surface region forming a skin which is primarily continuous and has a flanged or flared rear end that limits the depth of insertion of the earplug into the ear and provides a region to be grasped to remove the earplug.
U.S. Pat. No. 4,160,449 (Wade) discloses an earplug comprising a generally cylindrical plug of soft compressible resilient spongy material, such as elastomeric foam, having a diameter in relaxed condition slightly larger than the canal of a human ear. The plug is encased in an envelope of thin flexible plastic material which extends lengthwise beyond the end of the plug. The envelope is twistable to compress the plug and thereby reduce its size so as to facilitate introduction of the plug into the human ear canal. The envelop can be open to the atmosphere to permit air to be expelled when the envelop is compressed and twisted, or the envelop can be sealed and evacuated.
U.S. Pat. No. 5,044,463 (Carr) discloses a bullet-shaped molded foam earplug which is provided with a cavity extending from the flanged base axially into the earplug. The cavity provides an earplug which exerts less pressure on the ear canal than an earplug containing no cavity, thus, making the earplug more comfortable.
U.S. Pat. No. 4,579,112 (Scott) discloses an earplug which does not enter the ear canal but which merely blocks the entrance of the canal. The plug is made of a closed cell elastomeric foam having a tear drop ellipsoid shape when viewed from the side. The plug is slightly compressed and placed in a clocking position behind the tragus.
U.S. Pat. No. 4,219,018 (Draper, Jr.) disclosed an earplug unit with an inserter and tie adapted to be worm as a unit comprising one or a pair of earplugs each having a relatively flexible stem portion and adjacent spaced flanges of varying size made of relatively soft, yieldable, resilient material which readily conforms to sealingly engage the wall of the auditory canal of an ear. Each earplug has outer end attached to one or both ends of a tie member on which is slideably carried and retained an earplug inserter movable from a carrying position into engagement with the outer end of an earplug for its insertion into the auditory canal of an ear.
U.S. Pat. No. 4,321,998 (Van de Walker et al.) discloses a combined protective case and inserter for earplugs which has a cover held in a closed or an open position by a frictional backing feature, and can be reversed whereby either one of two earplug inserting means are exposed externally for the case for aiding the insertion of the earplug into a users ear. The earplugs useful with the invention are flange-type earplugs similar to those described in Draper, Jr.